The present invention relates to a semiconductor device manufacturing apparatus and, more particularly, to a manufacturing apparatus suited for use in a photolithography step for forming a plurality of pattern layers on a semiconductor substrate.
In manufacturing a semiconductor device, the step of stacking an upper pattern layer on a lower pattern layer formed on a semiconductor substrate is required. In this step, a photolithography step utilizing photography is used. In the photolithography step, when the upper pattern layer is to be exposed, so-called alignment of accurately aligning the upper pattern layer with the lower pattern layer must be managed at high accuracy. To realize a high alignment accuracy, a technique of measuring and storing a latent alignment accuracy offset of an exposure device itself in advance, and performing correction on the basis of the stored accuracy offset in actual exposure has conventionally been proposed. This technique is disclosed in, e.g., Japanese Patent Laid-Open Nos. 64-39726 and 63-80529. In addition, a technique of exposing a wafer called a pilot wafer or test wafer, and feeding back and correcting a positional accuracy obtained from the result in actual exposure has been proposed. This technique is disclosed in, e.g., Japanese Patent Laid-Open No. 1-120819.
The conventional technique described above is effective for an offset generated uniquely to some extent such as the latent offset of the exposure device. Today, however, the product design rule becomes stricter, and an offset between subsidiary materials which should produce the same result cannot be ignored. Accordingly, the influence of an offset generated in the process also becomes serious, and the alignment cannot be managed at high accuracy by the correction function of only the exposure device. The technique using a test wafer is advantageous in correcting an offset in the exposure device or the process. However, another wafer cannot be processed during processing of the test wafer, measurement, and feedback of data, resulting in low processing ability of the exposure device.